This invention is related to the art of air freshening air filters adapted to be used in forced air type heating and cooling systems. Particularily, what is disclosed and described herein is an integral disposable combination air filter and air freshening element to be used in a mechanical forced air type ventilation system.
Because of the increased use in forced air heating and cooling systems in residential and commercial establishments, and because these establishments are not supplied with a continuous supply of fresh air from outdoors, or if so, because the air outside of such establishments may be contaminated with undesirable particulate matter or odors, there is an increased need or desire to maintain the more pleasant environment in locations of human habitation. Moreover, the inpracticalities of open cycle ventilating systems wherein the forced air is not recirculated within a closed system during winter or summer months due to heating and cooling considerations have further increased the need or desire to freshen or disinfect the air of a closed cycle ventilating system. Not only do outside air temperature and air quality factors prevent open cycle ventilation for fresh air, but other factors, such as cooking, dust accummulation, and certain other unpleasant household and industrial chemicals has increased the desire for air filtering and freshening devices.
Additionally, with the recognition of deleterious environmental effects caused by aerosol air fresheners and germicides, other means of accomplishing air "conditioning" have been sought. In this regard, solid or liquid aromatic air fresheners and germicides have penetrated the market as an alternative, however, their effectiveness in freshening or sterilizing is minimal, as the disbursement of the aromatics are somewhat restricted, depending upon the air circulation in close proximity thereto. Incense has also been utilized to obviate the use of aerosols, but undesirable fire and smoke pollution hazards accompany their use.
It has long been recognized that air freshening and disinfecting can be accomplished by the incorporation or air freshener or air disinfecting elements within an air filter. In this respect, the applicant has noted U.S. Pat. No. 3,902,877 issued to Swaim on Sept. 2, 1975 wherein a container for air treating agents is disclosed. Means are provided for the disposition of a container filled with an air treating substance embedded within the filter elements. The container may be filled with a substance of the user's choice and be refilled for additional use with the same or a replacement air filter.
The applicant has also noted U.S. Pat. No. 3,820,308 issued to Onuki on June 28, 1974 wherein a sterilizing air filter is disclosed having a sterilizing agent coated directly on the filter elements. Unlike the Swaim patent, the entire filter element is disposable.
There are certain drawbacks with the prior art concerned with combination air filter and air freshening filters in that they may be relatively expensive or inefficient for reasons to be heretofore discussed. It is, of course, convenient and desirable to utilize disposable air filter units inasmuch as the maintenance effort is substantially reduced or eliminated. Although a non-disposable type may provide freedom of choice in the type of air freshener or disinfectant, this advantage may be gained in a disposable type by the provision of a variety of air filters having different type air fresheners or disinfectants.
Additionally, other types of combination air filters and air freshener or disinfecting agents wherein the air freshener or disinfecting substance is disposed directly on the filter elements have another significant drawback. That is, since the purpose of the air filtering elements is to trap particulate matter on the filtering fibers, there is a tendancy towards reduced odorizing or disinfecting efficiency with time due to a continuous reduction of exposed fiber surface area as the particulate matter within the filter increases. The odorizing or disinfecting effect of the container filled with a air freshener substance may also be reduced due to dust clogging or coating.
Thus far, the prior art has not revealed the most efficient means for accomplishing the dual function of air filtering and air freshening and/or disinfecting.
The prior art also discloses several means of producing such dual function air filters. The most common, as disclosed by the Swaim patent, is the provision of a separate ordoring element within or about the filter element. Treatment of the filter elements is also disclosed. These methods have not proved to be the most economical and efficient.